Understanding the Types of Lights You’ll See After Dark

*Altitudes are approximate and can vary by object.

How to Differentiate Stars from Artificial Lights

1. Stability – stars never flicker (aside from atmospheric scintillation). If a point of light twinkles noticeably, it is likely a star or planet, not an aircraft.
2. Color temperature – Stars emit a steady white or blue‑white hue; most aircraft navigation lights are red/green, while drones often use multi‑colored LEDs.
3. Speed of movement – A satellite crosses the sky in 3‑10 minutes, moving at a constant speed without turning. An airplane may change direction,climb,or descend,and its beacon flashes at 40-80 Hz.
4. Altitude clues – Use a smartphone app (see “Apps & Tools” below) to estimate altitude; objects below ~15 km are almost always human‑made.

Identifying Common Satellite Passes

• International Space Station (ISS) – the brightest satellite, often visible before sunrise or after sunset. Look for a steady white light moving quickly across the sky without flashing.
• Starlink constellations – appear as a “train” of ~20-30 lights traveling in formation. each dot is a small satellite; they may flicker slightly as they tumble.
• Iridium flares (phased‑out in 2023) – historically produced bright,brief flashes. Modern equivalents are Sun‑glint events from large solar panels (e.g., OneWeb).

Practical tip: Visit Heavens‑Above or use the “Satellite Tracker” feature in the *SkyView app to receive real‑time pass predictions for your latitude and longitude.

Spotting Airplane Lights with Confidence

• Beacon (red) vs. navigation (red/green) vs. anti‑collision (white) lights – the beacon flashes rapidly (≈6 Hz) and is usually visible from all directions. navigation lights are steady and show the left‑right color distinction.
• Altitude clues – If you can see the aircraft’s shadow on the ground,it is likely below 4 km.
• Flight routes – Commercial airways tend to follow predictable corridors (e.g., east‑west routes over the Atlantic). Use a flight‑tracking website like Flightradar24 to correlate a visible light with a known flight number.

Real‑world example (2024): A skywatcher in Denver observed a bright white object moving eastward at 8 km altitude.By checking Flightradar24 at the same timestamp, the object matched United Flight 877, confirming the light was an aircraft rather than a satellite.

Recognising Drones and other Low‑Altitude Lights

• Hovering behavior – Drones can stay stationary for extended periods, a behavior never seen in satellites.
• Pulse pattern – Many consumer drones flash an alternating red/green LED for orientation; some newer models use GPS‑linked “swarm” lighting, creating a circular pattern.
• Altitude limitation – In the United States, the FAA restricts recreational drone flights to ≤122 m (400 ft). If the light is consistently below this ceiling, it is almost certainly a drone.

Practical tip: Use a binoculars set with a 10× magnification to inspect the lighting pattern. Drones often reveal a visible frame or propeller silhouette when viewed up close.

Leveraging Technology: Apps, Star Charts, and Online Resources

How to use them together:

1. Open SkySafari to set your location and enable “satellite view”.
2. Switch to “night mode” and note any bright moving points.
3. Cross‑reference with Heavens‑Above to see if a satellite pass is scheduled for that time window.
4. If the object moves slower or hovers, launch DroneWatcher or Flightradar24 to rule out drones or aircraft.

Practical Tips for Accurate Night‑Sky Light Identification

1. Choose a dark site – Light pollution can mask faint stars and make satellite trails harder to see. use the Light Pollution Map (www.lightpollutionmap.info) to find a Bortle class 3-4 location within 30 km of your home.
2. Allow your eyes to adapt – wait 15-20 minutes after turning off all bright screens. Avoid looking at phone displays; use a red‑filter flashlight if needed.
3. Use a consistent reference point – Identify a bright star (e.g., Sirius) or a familiar constellation to gauge movement direction.
4. Record observations – A simple notebook entry with date, time, location, and description (color, flicker, speed) creates a searchable log for future reference.
5. Stay updated on launch schedules – New satellite constellations (e.g., SpaceX’s Starlink V2) add more objects to low Earth orbit. NASA’s Launch Schedule page lists upcoming deployments that may affect nightly visibility.

Benefits of Mastering Night‑Sky Light Identification

• Enhanced safety – Recognising low‑altitude drone traffic can prevent accidental collisions for hobbyist astronomers using motorized mounts.
• Improved stargazing experience – Differentiating between stars and transient lights reduces frustration and helps you focus on deep‑sky objects.
• educational value – Understanding orbital mechanics, aviation lighting standards, and atmospheric physics deepens your scientific literacy.
• Community contribution – Accurate citizen reports to platforms like Heavens‑Above improve satellite prediction models for everyone.

Quick Reference Cheat Sheet